Process of mordanting animal fiber.



Nrrsn STATES OTTO P. AMEND, OF NEW YORK, N. Y.

PROCESS OF MORDANTING. ANIM ALFIBER.

SPECIFICATION forming part of Letters Patent No. 700,284, dated May 20, 1902. Application filed March 5, 1898. Serial No. 672,629. (No specimens):

T0 00% whom it may concern:

Be it known that I, OTTO P. AMEND, a citizen of the United States, and a resident of New York, in the county and State of New York, have invented a certain new and Improved Process of Mordanting Animal Fiber, of which the following is a specification.

My invention relates to the art of dyeing animal fiber, whether wool fiber, silk fiber, hair, or other animal fiber.

It consists in producing a mordant upon the fiber at comparatively low temperature and without the boiling of the fiber heretofore employed by treating it in a free chromicacid bath in the absence of a non-oxidizing acid and thereafter reducing the ch r0 mic acid on the fiber by suitable means.

It also consists in producing a mordant on such fiber by treating it in a free chron1icacid bath in the absence of a non-oxidizing acid and without the boiling of the fiber, whereby without separate treatment by a special reducing agent the fiber is made ready for the reception of dyes, which of themselves operate to reduce the chromic acid on the fiber. The aromatic amins or their salts are substances of such character as will of themselves reduce the chromic acid on the fiber and may be fixed on the fiber without previously treating the fiber'with a special reducing agent.

In my prior United States patent, No. 512,264, granted to me January 9, 1894, I described and claimed a new process for producing a mordant on animal fiber, in which process there was employed a chromic-acid bath below boiling temperature, a nonoxidizing acid being used in the bath with the acid. I have since discovered, however, that the presence of such non-oxidizing acid is not always essential to the efficient production of the mordant.

The present invention is based chiefly upon the discovery that the use of the non-oxidizing acid may be dispensed with.

In carrying out the process the fiber is first treated, as by immersion, in a bath containing free chromic acid and which does not contain a non-oxidizing acid. The strength of this chromic-acid bath may considerably vary. I have used successfully a fivepercent. (0.05) solution; but I may also use a very weak solution-for example, a solution of one-thirtieth of one per cent. (0.00033) in re-- lation to the bath. In general where thesube sequent reductionis'performed in the chromic-acid bath I prefer a weaker solution; but if the subsequent reduction is performed in a in the solution forming the bath, or may ob-.

tain the chromic-acid solution many other suitable way. In this step of the process it is my purpose to obtain a chemical union of the fiber and free chromicacid'that is, a chromic-acid fiber compound"and it is important and essential to my process that the fiber be not oxidized by the chromic acid.

Heretofore in all cases, so far as known, where chromic acid has been used or proposed in mordanting or treating animal fiber for dyeing purposes the fiber was oxidized in.

the presence of the chromic acid, and such oxidation was deemed essential to the production of the results sought. Moreover, in

the practical art it has been customary toboil the fiber in the presence of the chromic acid. This oxidation of the fiber and this boiling are purposely avoided in my process, and the attending results are unquestionably. highly advantageous. I do not, therefore, boil the bath in the presence of the fiber, nor do I subject the fiber to boiling in the presence of the chromic acid at any time. careful also not to raise the temperature of the bath or the temperature of the fiber to a maximum point such that the fiber would be oxidized in the presence of the chromic acid. So long as this maximum temperature is not reached the temperature of the bath while the fiber is being treated may vary greatlywithout departure from the process. The maximum allowable temperature will of course vary with the different characteristics of different fibers under treatment. Ordinary temperature that is, ordinary dye-house temperature-although it may vary greatly in difierent dyehouses and at different times, will be generally found the most advantageous, as the Iain,

carrying out of the process will not of itself require any extra expenditure for fuel or steam. About 160 Fahrenheit I have found to be generally the maximum allowable temperature of the chromic-acid treatment, temperature above this point causing generally the injurious oxidation which I seek to avoid.

In preparing the fiber for treatment in a dye-bath of wood dyes, dyes of the alizarin series, and such other dyes which of themselves do not operate to effectually reduce the chromic acid on the fiber I complete the mordant by subjecting the fiber to the action of a suitable reducing agent. This reducing agent may be acid, alkaline, or neutral in character and may vary considerably in strength. I have used reducing-baths successfully which varied in strength from onehalf of one per cent. (0.005) to one-fifth of one per cent. (0.002) of the bath and have satisfactorily used an aqueous solution of sulfurous acid as a reducing agent. Sulfureted hydrogen, ferrous sulfate, cuprous chlorid, formic acid, lactic acid, or other reducing agent may be employed. In practice the reducing agent is preferably added to the chromic-acid bath containing the fiber,which then remains in the red ucing-bath until there is fully produced the reducing efiect desired that is to say, the chromic-acid fiber compound is reduced to a chrome-oxid fiber compound. This result will generally be produced advantageously in from half an hour to an hour, the fiber turning from a yellowish to a greenish tinge in the case of white or gray material.

It will be found that the fiber mordanted as above described will be prepared for the reception of any of the dyes which produce lakes with metallic compounds. Such dyes may be applied to the mordanted fiberby any process. The mordant thus produced is especially valuable in dyeing wool.

In cases Where it is desired to treat the fiber in a dye-bath which of itself efiects the reduction of the chromic acid on the fiber such, for example, as dye-baths of the aromatic amins or their saltsthe mordanting process is completed by means of the chromicacid treatment above described and without subjecting the fiber to a treatment by a special reducing agent.

The mordants produced by my process as above described are of great value and are produced, moreover, at a much less cost than that of the mordants heretofore in general use, all of which require boiling, with its attendant deleterious results.

Of course various changes may be made in the strength, duration, and temperature of the baths of the diiferent steps, and I wish it to be understood that my invention is not limited in these respects to any precise formula. The precise formula most advantageous in any particular case must be left largely to the judgment of the dyer, and such formula will depend for the most part upon the character and physical condition of the particular fiber under treatment. In general it will be found that a stronger bath will not require so long a treatment of the fiber in that bath and that the maximum allowable temperature of the first bath must be lower to prevent oxidation of the fiber when stronger chromic-acid solutions are employed.

What I claim as new, and desire to secure by Letters Patent, is

1. In the production of a mordant on animal fiber for dyeing, the process of treating the fiber with a solution of free chromic acid, the treatment taking place at such temperature as will not of itself substan tially produce an oxidation of the fiber under treatment.

3. The process of producing a mordant on animal fiber for dyeing, which consists in first treating the fiber With a solution of free chromic acid, and, second, in thereafter treating the fiber with a suitable reducing agent, the treatment taking place at such temperature as will not of itself substantially oxidize the fiber under treatment.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

OTTO I. AMEND.

Witnesses:

.IAs. C. HOWELL, NICHOLAS M. GOODLETT, J r. 

